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NGC 1850
NGC 1850
	A Hubble Space Telescope (HST) image of NGC 1850.
Observation data (J2000.0 epoch)
Constellation	Dorado
Right ascension	05h 08m 50.190s
Declination	−68° 45′ 35.65″
Apparent magnitude (V)	9.0
Apparent dimensions (V)	3.4′
Physical characteristics
Mass	41,700+10,800; −8,600 M☉
Radius	16.2 ± 1.1 ly (4.97 ± 0.35 pc)
Tidal radius	9.82 ± 0.39 ly (3.01 ± 0.12 pc)
	= −0.3 dex
Estimated age	~100 Myr
Other designations	NGC 1850, ESO 056-SC070, h 2780, GC 1060
	See also: Globular cluster, List of globular clusters

NGC 1850 is a double cluster and a super star cluster in the Dorado constellation, located in the northwest part^[3] of the bar of the Large Magellanic Cloud,^[4] at a distance of 168 kly (51.5 kpc) from the Sun.^{[citation needed]} It was discovered by Scottish astronomer James Dunlop in 1826.

This is an unusual cluster system because the main distribution of stars is like a globular cluster, but unlike the globular clusters of the Milky Way it is composed of young stars. The only similar object in the Milky Way is Westerlund 1.^[5] The main cluster has the appearance of a globular cluster with an age of 50±10 Myr. The second is a more loosely distributed sub-cluster with an age of 4.3±0.9 Myr,^[4] located at an angular separation of 30″ to the west of the main cluster.^[6] There are indications of interactions between the two, with the larger component being irregular and showing a tail toward the northwest.^[3]

The main cluster is around 100 million years old,^[2] with a tidal radius of 10 light years and an overall radius of 16 light years.^[2] It has an estimated mass of 42,000 times the mass of the Sun.^[2] The stellar component is split into two main sequence populations, with about a quarter of the stars in a blue (hotter) group and the rest in a redder (cooler) population.^[2] The cluster is embedded in an ionization region designated Henize 103.^[7]

The much younger subcluster, often designated NGC 1850A,^[3] contains a number of young, massive O/B-type stars that are on or near the main sequence, distributed up to 1′ from the central clump. Seven subcluster members have masses of ≥ 35 M_☉, and two of those are ≥ 50 M_☉. Lower mass members up to ~3 M_☉ are still on the pre-main-sequence stage. The age distribution of the subcluster members indicate star formation has been active almost constantly since its formation. The eastern side of the cluster is more obscured and has fewer OB stars.^[6]

In November 2021, astronomers using MUSE on the Very Large Telescope reported the discovery of a stellar-mass black hole in NGC 1850 by viewing its influence on the motion of a star in close proximity, the first direct dynamical detection of a black hole in a young massive cluster.^[8]

Gallery

ESO image of NGC 1850 showing the stellar cluster and surrounding nebulosity

References

^ ^a ^b Werchan, Felicia; Zaritsky, Dennis (August 2011). "The Star Clusters of the Large Magellanic Cloud: Structural Parameters". The Astronomical Journal. 142 (2): 10. arXiv:1105.1769. Bibcode:2011AJ....142...48W. doi:10.1088/0004-6256/142/2/48. S2CID 118331608. 48.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Correnti, Matteo; et al. (May 2017). "Dissecting the extended main-sequence turn-off of the young star cluster NGC 1850". Monthly Notices of the Royal Astronomical Society. 467 (3): 3628–3641. arXiv:1612.08746. Bibcode:2017MNRAS.467.3628C. doi:10.1093/mnras/stx010.
^ ^a ^b ^c Westerlund, Bengt E. (February 27, 1997). King, Andrew; Lin, Douglas; Pringle, Jim; Ward, Martin; Maran, Stephen (eds.). The Magellanic Clouds. Cambridge University Press. ISBN 9780521480703.
^ ^a ^b Gilmozzi, R.; et al. (November 1994). "WFPC2 Observations of the Double Cluster NGC 1850 in the Large Magellanic Cloud". Astrophysical Journal Letters. 435: L43. Bibcode:1994ApJ...435L..43G. doi:10.1086/187590.
^ Gallagher, J. S.; Grebel, E. K. (2002). Geisler, D.; Grebel, E. K.; Minniti, D. (eds.). Extragalactic Star Clusters: Speculations on the Future. Extragalactic Star Clusters, IAU Symposium. Vol. 207. Astronomical Society of the Pacific. p. 745. arXiv:astro-ph/0109052. Bibcode:2002IAUS..207..745G.
^ ^a ^b Caloi, V.; Cassatella, A. (February 1998). "Evolutionary status and age spread in the young LMC cluster NGC 1850A". Astronomy and Astrophysics. 330: 492–504. Bibcode:1998A&A...330..492C.
^ Fischer, Philippe; et al. (March 1993). "Dynamics of the Young Binary LMC Cluster NGC 1850". Astronomical Journal. 105: 938–944. arXiv:astro-ph/9210004. Bibcode:1993AJ....105..938F. doi:10.1086/116483. S2CID 119484423.
^ "Black hole found hiding in star cluster outside our galaxy". ESO. 11 November 2021. Retrieved 11 November 2021.